Exotic invasive species are the enemies of conservation land managers. I'll start the discussion with two vines and a grass. Lygodium can be a problem, but I've found only two spots and eliminated both quickly. Abrus is everywhere, but it has always been around and I can live with it, I think.
Natal grass is a major nuisance. It has taken over major sections of the fire lanes that aren't already taken over by something else. There are other exotic problems. I'll post their mug shots later.
